At present, with high requirements for integration of a communication system, it has become a developing trend to directly multiply the number of slots with a double-sided pluggable backplane in backplane technology. Multiplication of the number of slots improves balancing of configuration granularity of system services on a board, directly leading to flexibility and reliability of design as well as feasibility for multi-production integration.
FIG. 1 schematically illustrates connection of a double-sided pluggable backplane and boards according to the prior art. As shown in FIG. 1, a front board 100 is plugged into a front backplane connector 111 of a double-sided pluggable backplane 110 by means of a plug 101, and a rear board 120 is plugged into a rear backplane connector 112 of the double-sided pluggable backplane 110 by means of a plug 121. Front board 100 is in alignment with the corresponding rear board 120. However, front backplane connector 111 and rear backplane connector 112 are located at different horizontal levels, meanwhile plug 101 of front board 100 and plug 121 of rear board 120 are located at different horizontal levels too, i.e. they are staggered up-and-down. Although front backplane connector 111 and rear backplane connector 112 can have uniform definitions for interface contact pins, yet they have different horizontal locations, thus front board 100 and rear board 120 can not be interchangeable on a double-sided pluggable backplane.
It could be seen this kind of double-sided pluggable backplane has an insurmountable disadvantage. More specifically, a board in a front slot cannot be interchanged with that in a rear slot, which is similar to back-to-back integration of two frames in essence.
Aiming at the above disadvantage, a design idea has been proposed that adopts special backplane connectors to make boards interchangeable at fore-and-aft slot positions.
FIG. 2 is a schematic diagram illustrating an interchangeable double-sided pluggable backplane and boards according to the prior art. As shown, a front board 200 is plugged into a front backplane connector 211 of a double-sided pluggable backplane 210 by means of a plug 201, and a back board 220 is plugged into a rear backplane connector 212 of double-sided pluggable backplane 210 by means of a plug 221. Both of front backplane connector 211 and rear backplane connector 212 comprise a power supply interface and a signal interface, and they are located at the same horizontal level. Meanwhile, front backplane connector 211 and rear backplane connector 212 have uniform definitions for interface contact pins, so front board 200 and rear board 220 are interchangeable on the backplane.
Here, front backplane connector 211 and rear backplane connector 212 on double-sided pluggable backplane are the same special backplane connectors, and they are aligned in the up-and-down position and fore-and-aft position absolutely. The depth of the contact pins of front backplane connector 211 and rear backplane connector 212 must be less than or approximately equal to half of the thickness of the backplane, and the contact pins must be insulated from each other.
The above-mentioned double-sided pluggable backplane has rather high requirements for its circuit board. The thickness error of the circuit board must be exceedingly tiny, otherwise it cannot be guaranteed that the depth of the contact pins of the special backplane connectors is less than or approximately equal to half of the thickness of the backplane and that the contact pins are insulated from each other. The speciality of the backplane connector, along with the special requirements for designing, manufacturing of the printed circuit board in the backplane and machining of the backplane directly bring about some insurmountable difficulties, such as costliness, difficulty in processing and so on. Therefore this kind of double-sided pluggable backplane is still in the stage of designing rather than being applied in practical manufacturing.